A variety of techniques related to manufacturing of carbon nanotubes (hereinafter referred to also as “CNTs”) have been reported.
Within a method of manufacturing CNTs using a CVD method, Kenji Hata et. al., “Water-Assisted Highly Efficient Synthesis of Impurity-Free Single-Walled Carbon Nanotubes”, SCIENCE, Nov. 19, 2004, VOL. 306, pp. 1362-1364 (NPL 1) disclose a technique for dramatically increasing the activity and lifetime of a catalyst by placing the catalyst in contact with a catalyst activating material, such as water, along with source gas.
WO 2010/092787 (US 2011/0308462 A1) (PTL 1) discloses a manufacturing apparatus that manufactures CNTs, in which an apparatus component that is exposed to a reducing gas or a source gas is plated with molten aluminum so as to decrease the quantity of carbon contaminants that adhere to the apparatus component.
Furthermore, WO 2010/076885 (EP 2 383 225 A1) (PTL 2) discloses manufacturing CNTs efficiently by adjusting the ratio between the number concentration of carbon atoms in the source gas and the number concentration of oxygen atoms contained in the catalyst activating material.
JP 2011-241104 A (PTL 3) discloses manufacturing high-quality CNTs by controlling the flow rate of hydrocarbon gas, based on the results of analyzing a gas component in the catalyst activation zone, the synthesis zone, and the cooling zone, to set the hydrogen gas concentration in the catalyst activation zone to be 80% or more.